Field of the Invention
The inventions disclosed and taught herein relate generally to wet/dry vacuum appliances, and more specifically, are related to a bypass vent system for use with wet/dry vacuum appliances.
Description of the Related Art
Vacuum appliances capable of picking up both wet and dry materials, commonly referred to as wet/dry vacuums, are generally well-known. Such vacuums with both wet and dry capabilities are often used in workshops, basements, garages, and other environments where both wet and dry debris can accumulate and needs to be collected for separate disposal.
Wet/dry vacuums conventionally consist of a collection tank or canister, sometimes mounted on wheels or casters, and a cover or lid upon which a motor and impeller assembly is mounted. The motor and impeller assembly creates a suction within the canister, such that debris and liquid are drawn in to the canister through an air inlet to which a flexible hose can be attached. A filter within the canister prevents incoming debris from escaping from the canister while allowing filtered air to escape. One example of such an exemplary wet/dry vacuum is shown in U.S. Pat. No. 4,797,072.
In the usual canister- or tank-type vacuum cleaners that are used for collecting various types of material, they are sometimes used for collecting water or other liquid debris. In a typical vacuum cleaner of this type, the vacuum cleaner motor is supported on a removable lid for the debris collection drum and drives an impeller fan having an inlet side that communicates with the drum interior and draws a vacuum therein, allowing water or liquid debris to be drawn into the collection drum by way of a vacuum hose or the like.
In the usual canister vacuum cleaner, the lid is a generally flat surface disc or plate. To provide the lid with the strength needed for supporting the motor, especially while it is in operation, and for supporting an air filter assembly, the lid is typically formed of a strong, relatively rigid polymer or metal disc having a periphery that is shaped to sealingly engage the upper end of the side wall of the cylindrical tank or drum. A hole is cut through the lid just beneath the mounting for the motor and this hole provides communication between the interior of the tank and the impeller fan driven by the motor.
A filter assembly is interposed between the interior of the tank and the inlet to the impeller fan for capturing particulate matter so that it does not escape into and past the fan and is not expelled from the vacuum cleaner. In the typical tank vacuum cleaner, directly beneath the lid of the tank and at the inlet to the impeller fan, there is a support for a replaceable filter element. Typically, the filter support is in the form of a generally cylindrical cage, and the filter element is in the form of a cylindrical annulus or sleeve of open cell foam material which is removably fitted over the filter cage. The annular sides of the filter cage are defined by vertical ribs, shaped and placed to support the surrounding filter element, yet spaced apart so as not to interfere with air flow. The bottom of the filter cage is closed off.
In situations where liquid or wet materials are being collected, it is necessary that the flow out of the tank and into the vacuum cleaner motor be halted before the liquid or wet material is drawn into the motor. This is typically effected by way of a float element located within a filter cage assembly. The filter cage of the typical canister vacuum cleaner is secured to the underside of the lid around the hole through the lid, and is included for the purpose of supporting a cylindrically-shaped filter element. Typically, the filter cage is a molded plastic unit with an annular collar at its upper edge, and may be of cylindrical, oval, or numerous other shapes, as appropriate. Inside the filter cage, there is a ball or cylinder float element that sits on the base of the filter cage and is adapted to float up within the filter cage once the level of liquid in the tank rises above the bottom of the filter cage. The float element eventually floats high enough to seal the inlet to the impeller fan. Further operation of the vacuum cleaner is blocked until the tank is emptied of collected material. At the same time, the filter element may also be replaced if so desired by the user.
The prior art has described various types of devices that automatically indicate when the debris or liquid level in a vacuum cleaner has reached a critical level, thereby alerting the operator of the problem so that operation of the vacuum may be stopped, and the canister emptied. At that point, continued operation of the vacuum cleaner will result in ineffective or inefficient cleaning, or even worse, it may cause damage to the motor and fan unit. Illustrative patents describing such approaches include U.S. Pat. No. 2,230,113 to Hein; U.S. Pat. No. 2,758,670 to Doughman et al; U.S. Pat. No. 2,764,256 to Allen; U.S. Pat. No. 2,814,358 to Beede et al; U.S. Pat. No. 2,817,414 to Ferraris; U.S. Pat. No. 2,863,524 to Buda; U.S. Pat. No. 3,172,743 to Kowalewski; U.S. Pat. No. 3,626,545 to Sparrow; U.S. Pat. No. 3,870,486 to Eriksson et al; U.S. Pat. No. 4,246,676 to Hallsworth et al; U.S. Pat. No. 4,294,595 to Bowerman; and U.S. Pat. No. 4,623,366 to Berfield et al.
The prior art vacuum cleaner dirt level detection devices can be divided into two general categories. These devices have either floats that are designed to operate in vacuum cleaners which pick up liquids, or they have diaphragm devices that are affected by the difference in pressure between two points in the vacuum cleaner caused by the clogging of a vacuum cleaner dirt collecting bag. When the pressure differential reaches a threshold, the diaphragm triggers a sequence of mechanical or electrical steps which result in either the dust bag cover opening, a light or audible signal warning the operator to shut down the vacuum cleaner, or automatic powering down of the motor fan unit. U.S. Pat. No. 4,623,366 to Berfield is representative of the devices having a float-based system. The float devices rely generally on the principle of buoyancy which causes a float to rise and seal against a seat when a sufficient amount of water has accumulated in the collection container of the vacuum cleaner. The float blocks the fan inlet opening so that even if the motor fan unit continues to run, additional water is not pulled into the system. These float devices are thus not designed to operate by sensing a differential air pressure on opposed sides of a valve.
U.S. Pat. No. 2,817,414 to Ferraris is a typical vacuum cleaner employing a differential pressure diaphragm, or sensor, which acts to detect an increase in pressure between two points in the vacuum cleaner. In the Ferraris device, pressure readings are taken between the inside and the outside of a dust collecting bag. As the bag fills with dirt, a differential force is exerted upon a control diaphragm. At a predetermined threshold, the diaphragm distorts and sets in motion a sequence of pneumatic, mechanical and/or electrical steps which de-energize the motor fan unit. These latter type of control devices, while addressing the issue, are both complicated and expensive to manufacture.
As shown in U.S. Pat. No. 4,185,974, a canister- or tank-type vacuum cleaner which uses a generally cylindrical filter element that is fitted around a generally cylindrical filter cage is described, wherein the cage is an integral plastic molding with the lid that closes the tank of the vacuum cleaner; the vacuum cleaner motor sits atop the lid; the lid is removably sealed to the canister; and, inside the filter cage, there is a freely floating ball, which floats up through the cage as the tank becomes filled to seal the air outlet to the motor. The bottom end of the filter cage is closed off by a bottom cover. An inlet grid element, including a grid covered opening, is disposed across the hole through the tank lid for permitting air to pass through the hole in the lid while also enclosing the top end of the filter cage as a safety feature to block access to the rotating impeller fan. A generally flat wall extends from the grid to the tank lid. The bottom edge of a sleeve extending downward from the grid constitutes a seat against which the float seals upon rising to a predetermined level. If the fan continues to operate after its inlet is blocked by sealing of the float against the seat, the fan motor overheats. This causes the molded plastic grid unit to overheat at a time when there is an upward force transmitted through the float to the sleeve portion of the grid unit. As a result, the grid unit distorts, often resulting in a faulty sealing between the float and seat at the bottom edge of the sleeve.
U.S. Pat. No. 4,623,366 describes a wet/dry canister-type vacuum cleaner that is provided with a plastic grid unit that includes a spherical cup-like main section, an upper annular mounting lip, a short tubular support disposed within the main section with the lower end of the support surrounding a central inlet opening in the latter, and a grid extending across the support at the top thereof and disposed below the mounting lip. The lower end of the support constitutes a seat for a floating ball valve element. An axially extending slot in the support provides a drain for liquid that may be accumulated by the main section at the interior thereof.
The inventions disclosed and taught herein are directed to an improved wet/dry vacuum appliance having a bypass vent system.